Interaction between anti-dip rock slope and anchor system under unloading effect: an experimental investigation

This study experimentally explores the interaction between an anti-dip rock slope and anchor system under unloading conditions. The slope-anchor system, created by inserting anchor bolts into the slope, displays a complex deformation and failure mechanism when subjected to unloading. The anchoring and deformation characteristics of this system are crucial for assessing slope stability and optimizing anchorage. Using the right slope at the Huangdeng Hydropower Station in China as a model, a scale model was constructed to investigate the deformation characteristics, stress distribution, and anchor force in an anti-dip rock slope-anchor system under unloading. The unloading effect was simulated through excavation during the test. The results indicate that both horizontal and vertical stress, as well as stress at shallow depth near the excavation site, decrease sharply upon excavation, while displacement increases rapidly, displaying a step-like pattern consistent with the excavation process. The anchor forces increase during excavation due to the rebound and deformation of the slope. The excavation influences the slope through the unloading effect, causing stress to decrease near the excavation part, while the effect of anchorage acts as a counterbalance against stress changes. Finally, a method for calculating the safety factor for the anchored slope is proposed. The safety factors derived from both experimental and on-site monitoring data exhibit similar trends. This enhanced understanding of the slope-anchor system under unloading conditions can inform more effective strategies for slope stabilization and anchorage optimization.